my hens only sit on their eggs after they lay.

Its been awhile since I've been on here, and since then some of my hens started laying, but seem to only sit on their eggs maybe 20 min after they lay them. How will the eggs hatch if the hens aren't on them? I don't want to have to incubate them.

My hens do the same thing ( I guess they want some time with their egg before departing) but this is not broody behavior, if a hen is broody she will walk around with puffed up feathers ( often mistaken as being a sick chicken) clucking in a weird fashion. If you stick you hand in a broody hens box they will hiss puff up their feathers or peck at you.